Znalazłam coś takiego:

"The first nightshots with the EOS 5D Mark II started promising but I was shocked when "error 30" showed up on the display. User manual told me to switch the cam off/on or remove battery. Did not work, when trying to take a pic it was black. Next suggestion was to send it in for service.
Solution:
I changed into LiveView and back - that resolved the issue and now I had no more errors so far."

- http://forums.dpreview.com/forums/re...=error+30&qf=m

Mam nadzieję, że pomoże.... Zaszkodzić nie powinno. Daj znać!